What is roller wave distortion ?
In order to ensure the correct properties of thermally toughened and heat strengthened glass they must be heated to above their softening point, usually in a horizontal roller hearth plant. When the temperature of the glass is above 650°C it becomes pliable and when the glass is oscillating back and forth in the heating stage it momentarily stops at each reversal. It is at this point that the glass between the rollers will slightly sag, resulting in a slight deviation from flatness which reveals itself as ripples or roller wave when viewed at an acute angle in reflection. This is inevitable and even though the processors strive to minimise the effect, it is an inherent part of the process.
